"I want to make it clear that I have nothing but the ultimate respect for Juan Castillo as a coach and as a person. He's one of the finest football coaches that I have ever worked with. He has served this organization extremely well for 18 years and letting him go was a difficult decision. I know he will continue to be a successful coach in this league and wish he and his family nothing but the best," Reid said in a statement released by the team.

"We're six games into the season and average isn't good enough. I know the potential of our team and insist on maximizing it."

Though much of the focus on Philadelphia's struggles has been its inability to hold onto the ball (17 turnovers), the 12th-ranked defense (330.8 yards allowed per game) has had its problems, too, especially when it comes to pressure. The Eagles' seven sacks are third-worst in the league and represent a stunning reduction for a team that produced a league-best 50 sacks in 2011.

Castillo's group also surrendered a 10-point lead with less than four minutes to go in Sunday's 26-23 overtime loss to the Detroit Lions left the Eagles at 3-3.

The defense struggled mightily last year, most notably while trying to stop the run with its Wide-9 scheme during the team's 4-8 start. It was Castillo's first working with the unit after spending the previous 15 seasons as an offensive assistant for Philadelphia.

"I put Juan in this situation, and things didn't work out as I'd hoped," Reid said in press conference Tuesday.

"I thought we were making progress, I saw us making progress," he added while declining to offer specifics. "And then I started seeing some trends come back that I wasn't real happy about. ... I didn't want to go in that direction."

Pass rush aside, the Eagles were decidedly average in most categories this season - 13th in points allowed (20.8), 15th against the pass (226.3 ypg), 15th vs. the run (104.5 ypg) and 19th with eight turnovers forced.

But average clearly won't cut it for Reid, who was put on notice by owner Jeffrey Lurie prior to the season that another disappointing year will likely mean Reid's 14th season at the helm will be his last.

"We go back, and we evaluate and tear things apart during this bye week and look at how we get ourselves better in both areas - as players and coaches. You evaluate everything and that's what we'll do from that standpoint," Reid said Monday. "With 10 games left, we know that there are a lot of games left. Anything is possible in the National Football League, and I still believe that we have a good football team. We just have to get a couple of things together here."

Regarding other major changes that might be in the works, Reid was evasive Tuesday.

"I haven't made any other moves other than this," he said. "Am I still evaluating? (Yes,) I'm still evaluating."